I have some pretty nasty spinal problems that cause me horrible, excruciating pain if I'm not careful.
The worst, however, was when I had steroid shots in an attempt to fix my collapsed disk. Basically, they take a long ass needle (Big enough to qualify as some sort of stabbing weapon), jab it into your back (More like from the side. They start something like 6 inches to the side of your spine, so you can imagine just how big that needle has to be), and then insert it all the way into your spine.
And then the shot steroids into the spine. From both sides.
When they did it to me, the started on the side that hadn't collapsed. I didn';t really feel anything, and they let me look at the live xray as they did it, which was kind of cool, in a perverse way (Yes, live xray. I got to watch, from the inside, as they jammed an 8 inch needle into my spine and played fill the balloon).
Then they did the side that had collapsed.
I have never felt such pain in my life. It basically put a huge amount of pressure on a spinal nerve. My left leg felt like it had been torn off, and my back was set aflame with gasoline. The worst part was the disembodied pain - It felt like I had an entire extra body floating about 2 feet behind me, and that extra body was being torn apart by Satan himself. It was terrible.
On the xray, I could see what the problem was. Asshole doctor was literally trying to inflate my collapsed disc. You could see steroid literally exploding out of my spine (Which looked really cool, but it was something I was not prepared to appreciate at that particular moment).